Method and apparatus for spectrum monitoring

ABSTRACT

A receiver is configured to be coupled to a television and data service provider headend via a hybrid fiber coaxial (HFC) network. The receiver comprises front-end circuitry operable to receive a signal that carries a plurality of television and/or data channels, and digitize the received signal to generate a digitized signal. The receiver comprises channelizer circuitry operable to select a first portion of the digitized signal, and select a second portion of the digitized signal. The receiver comprises processing circuitry operable to process the selected second portion of the digitized signal to recover information carried in the plurality of channels. The receiver comprises monitoring circuitry operable to analyze the selected first portion of the digitized signal to measure a characteristic of the received signal; and control the transmission of network management messages back to the headend based on the measured characteristic of the received signal.

PRIORITY CLAIM

This patent application is a continuation of U.S. patent applicationSer. No. 14/341,880 filed on Jul. 28, 2014 now patented as U.S. Pat. No.9,203,653, which is a continuation of U.S. patent application Ser. No.13/607,916 filed on Sep. 10, 2012 now patented as U.S. Pat. No.8,792,008, which also makes reference to, claims priority to and claimsbenefit from U.S. Provisional Patent Application Ser. No. 61/532,098filed on Sep. 8, 2011. Each of the above referenced documents is herebyincorporated herein by reference in its entirety.

INCORPORATION BY REFERENCE

This patent application also makes reference to:

U.S. patent application Ser. No. 13/336,451 titled “Method and Apparatusfor Broadband Data Conversion,” filed on Dec. 23, 2011, and published asU.S. Patent Application Publication No. 2012/0163518;

U.S. patent application Ser. No. 13/485,003 titled “Multi-layerTime-Interleaved Analog-to-Digital Converter (ADC),” filed on May 31,2012 and now patented as U.S. Pat. No. 8,611,483; and

U.S. patent application Ser. No. 13/588,769 titled “Multi-StandardCoverage Map Generation,” filed on Aug. 17, 2012, and now patented asU.S. Pat. No. 9,026,118.

Each of the above referenced documents applications is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to signal processing. Morespecifically, certain embodiments of the invention relate to a methodand system for spectrum monitoring.

BACKGROUND OF THE INVENTION

Network-based services can become unacceptable if network parametersfall outside of those for which receivers in the network were designed.For example, in a cable television system there are specifications forthe number of channels on the plant, the types of channels, the signallevels of those channels and the impairments that can be on the plantthat would affect the performance of the receiver. If some or all ofthese parameters deviate outside acceptable bounds, the user mayexperience unacceptable performance. Conventional methods andapparatuses for monitoring network parameters are too costly andimpractical for use in customer-premises equipment (CPE).

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for spectrum monitoring,substantially as shown in and/or described in connection with at leastone of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A depicts an example cable system in accordance with an exampleembodiment of the invention.

FIG. 1B depicts an example receiver operable to perform spectrummonitoring in accordance with an example embodiment of the invention.

FIG. 1C depicts an example satellite system in accordance with anexample embodiment of the invention.

FIG. 2A depicts an example RF front-end of a receiver operable toperform spectrum monitoring in accordance with an example embodiment ofthe invention.

FIG. 2B depicts another example RF front-end of a receiver operable toperform spectrum monitoring in accordance with an example embodiment ofthe invention.

FIG. 3 depicts an example channelizer which may be utilized forperforming spectrum monitoring in accordance with an example embodimentof the invention.

FIG. 4 is a flow chart illustrating example steps for spectrummonitoring in accordance with an example embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As utilizedherein, “and/or” means any one or more of the items in the list joinedby “and/or”. For example, “x and/or y” means any element of thethree-element set { (x), (y), (x, y) }. Similarly, “x, y, and/or z”means any element of the seven-element set {(x), (y), (z), (x, y), (x,z), (y, z), (x, y, z)}. As utilized herein, the terms “block” and“module” refer to functions than can be implemented in hardware,software, firmware, or any combination of one or more thereof.

FIG. 1A depicts an example communication system in accordance with anexample embodiment of the invention. Shown in FIG. 1 is a terrestrialtelevision antenna 102, a satellite dish 104, an Internet Protocol (IP)network 106, a headend 108, a wide area network (e.g., hybridfiber-coaxial (HFC) network) 118, a gateways 120 a and 120 b, endsystems 126 a and 126 b (e.g., computers), and end systems 128 a and 128b. The headend 108 comprises a switch 110, a video modulator 112, acable modem termination system (CMTS) 114, and a splitter/combiner 116.

For downstream traffic, the headend 108 may receive television signalsvia the antenna 102 and the satellite dish 104, and may receive data viathe IP network 106. The switch 110 may convey the television signals tothe video modulator 112 and the data to the CMTS 114. The videomodulator 112 may modulate the received television signals onto acarrier. The CMTS 114 may modulate the received data onto a carrier. Thesplitter/combiner 116 may combine the outputs of the video modulator 112and the CMTS 114 resulting in a frequency division multiplexed (FDM)signal comprising one or more television channels and/or one or moreDOCSIS channels. The FDM signal may be onto the wide area network (WAN)118 for distribution to customer premise equipment (CPE). Each of thegateways 120 a and 120 b may comprise a receive module 150 operable toprocess the received FDM signal as described below.

In an example embodiment, each of the gateways 120 a and 120 b may beoperable to transmit, via a module 152, messages to the CMTS 114. Forsuch upstream data, the gateways 120 a and 120 b may modulate messages(e.g., network management/maintenance messages) onto one or morecarriers for transmission via the WAN 118. The splitter/combiner 116 maythen convey the message to the CMTS 114. The CMTS 114 may process themessages and, in an example embodiment, adjust transmission parameters(e.g., modulation parameters, transmit power, frequency offsets, etc.)and/or perform other maintenance/management based on the receivedmessages.

FIG. 1B depicts an example receiver operable to perform spectrummonitoring in accordance with an example embodiment of the invention.Shown in FIG. 1B is a receiver circuit 100 comprising an RF receivefront-end module 158, a channelizer module 102, a monitoring module 154,and a data processing module 156.

The RF receive front-end 158 may be operable to process a received RFsignal S to generate a digital signal D. The signal S may be the resultof a plurality of television and/or DOCSIS channels being frequencydivision multiplexed into a single signal. The signal S may occupy afrequency band from F_(lo) to F_(hi). The RF front-end 158 may, forexample, amplify, down-convert, filter, and/or digitize the receivedsignal S to generate the digital signal D. Example embodiments of the RFfront-end are depicted in FIGS. 2A and 2B.

The channelizer 102 may be operable to select J+1 bands (represented asC₁-C_(J+1)) of the signal S and output each of the selected bands to themonitoring module 154 and/or the data processing module 156, where J isan integer greater than 1. An example embodiment of the channelizer 102is depicted in FIG. 3. Each band C_(j) may, for example, correspond tothe frequency band of one or more television channels. For example, eachband C_(j) may be an integer multiple of 6 MHz (U.S.) or 8 MHz (EU).

In an example embodiment, the channelizer 102 may be implementedentirely in the digital domain and the channelization may be achievedvia one or more digital filtering algorithms and/or other digital signalprocessing algorithms.

The monitoring module 154 may be operable to analyze the band C_(J+1)that it receives from the channelizer 102 to measure/determinecharacteristics such as, for example, signal power level vs. frequency,delay vs. frequency, phase shift vs. frequency, type and/or amount ofmodulation, code rate, interference levels, signal to noise ratio, atransfer function of the channel of over which the signal was received,an impulse response of the channel over which the signal was received,and/or any other characteristic that may help assess characteristics ofthe channel over which the signal was received, assess characteristicsof the transmitter that sent the signal and/or any otherwise bepertinent to performance of the communication system. The monitoringmodule may also be operable to generate one or more control signals 160for configuring the channelizer 102 and/or for configuring the RFfront-end 158. Additionally or alternatively, the control signal(s) 160output by the monitoring module 154 may control the transmission ofnetwork management/maintenance messages by the device 150. Such messagemay comprise, for example, network status updates indicating whether oneor more communication parameters of one or more received television orDOCSIS channels are outside acceptable bounds, and/or conveyingmeasured/determined characteristics back to a source of the receivedsignal (e.g., back to a cable headend), In an example embodiment, themonitoring module 174 may be operable to demodulate signals formeasuring one or more characteristics such as signal-to-noise ratio,code rate.

The data processing module 156 may be operable to process the bandsC₁-C_(J) conveyed to it by the channelizer 102 to recover data presentin one or more television channels present in those bands of the signalS. The data processing module 156 may, for example, performsynchronization, equalization, and decoding. The data processing module156 may output processed data (e.g., MPEG transport stream packetsand/or Internet Protocol packets) to end systems 126, perhaps via aninterface such as an HDMI interface and/or an Ethernet interface (notshown). The data processing module 156 may also be operable to generateone or more control signals 162 for configuring the channelizer 102and/or the receive front-end 158.

The parallel arrangement of the monitoring module 154 and dataprocessing module 156 may enable determination of signal and/or channelcharacteristics without having to interrupt service to user equipment126 and 128.

In an example embodiment, the signal S may be a cable television signalwith F_(lo)≈55 MHz, F_(hi)≈1002 MHz. In an example embodiment, thesignal S may be a MoCA signal with F_(lo)≈1150 MHz and F_(hi)≈2100 MHz.These numbers are purely for illustration and not intended to belimiting.

In an example embodiment, the signal S may be a satellite televisionsignal such as may be at the input of a LNB, at the output of a LNB, orat the input of a indoor unit (e.g., set top box). In such anembodiment, the front-end 158, channelizer 152, data processing module154, and/or monitoring module 154 may reside in the indoor unit (e.g.,set-top box), outdoor unit (e.g., satellite dish or accompanyingcomponents), and/or may be distributed among the indoor unit and outdoorunit of a satellite installation residing at a customer premises. Anexample of such an embodiment is shown in FIG. 1C.

In operation of such an example embodiment, the signal S may beamplified, possibly downconverted, and digitized by the RF front-end 158to generate the signal D. The channelizer 102 may then select J bands ofthe signal D for output to the data processing module 156. Each of theselected bands C₁-C_(J) may, for example, comprise one or more of thecable television channels and/or one or more of the DOCSIS channels thatmake up the signal S. The data processing module 156 may provide one ormore control signals to determine which portion of the signal D isselected for each of the bands C₁-C_(J). The selection may be based, forexample, on which television channels are being consumed by end systems128 and/or whether DOCSIS data is being consumed by end systems 126. Thechannelizer 102 may also select one band, represented as band C_(J+1),to be output to the monitoring module 154. Band C_(J+1) may comprise anyportion or portions (including the entire bandwidth from F_(lo) toF_(hi)) of the signal D. Which portion of the signal S is selected asband C_(J+1) may, for example, be configured by the monitoring module154. The data processing module 156 may process one or more of bandsC₁-C_(J) to recover data on one or more channels (e.g., televisionand/or DOCSIS channels) present in those bands while the monitoringmodule 154 may concurrently process band C_(J+1) to measure/determinecharacteristics of all or a portion of the signal S between f_(lo) andf_(hi).

FIG. 1C depicts an example satellite system in accordance with anexample embodiment of the invention. Shown in FIG. 1C is a satellitedish assembly 172, and a gateway 196. The subassembly 174 comprises afeed horn 182, an LNB 194, the front-end 158, the channelizer 152, themonitoring module 154, and the data processing module 156. The variousmodules of the subassembly 174 may reside in one or more housings, onone or more printed circuit boards, and/or one or more integratedcircuits (e.g., one or more silicon dice). In another exampleembodiment, the monitoring module 154 and/or the data processing module156 may reside in the gateway 196.

In the example embodiment depicted, the satellite dish assembly 172comprises a parabolic reflector 176 and a subassembly 174 mounted (e.g.,bolted or welded) to a support structure 178 which, in turn, comprises aboom 190 and attaches (e.g., via bolts) to the premises 180 (e.g., tothe roof). In another example embodiment, all or a portion of themodules 152, 154, and/or 156 may be mounted to the premises 180 separatefrom the satellite dish (e.g., connected via wired and/or wirelessconnections), but may still be part of the “outdoor unit.”

The gateway 196 may receive data from the satellite dish assembly 172(via cable(s) 184). The gateway and may transmit data onto and receivedata from the WAN 192 (via broadband connection 188). The gateway 196may transmit data to and receive data from user equipment 128 and 126(via one or more connections 186).

FIG. 2A depicts an example RF front-end of a receiver operable toperform spectrum monitoring in accordance with an example embodiment ofthe invention. The RF front-end 158A shown in FIG. 2A comprises avariable gain amplifier 202, and receive chains 204 ₁-204 _(L), where Lis an integer greater than or equal to 1. Each receive chains 204 ₁ maycomprise an amplifier module 210 ₁, a mixer module 212 ₁, a filtermodule 214 ₁, and an analog-to-digital converter (ADC) module 216 ₁,where 1 is an integer between 1 and L.

Each amplifier 210 ₁ may be operable to amplify a band 1 of the signalS. Each mixer 212 ₁ may be operable to mix a band 1 of the signal S witha local oscillator signal (not shown) to downconvert the band 1 to alower frequency. Each filter module 214 ₁ may be operable to bandpassfilter the band 1 to remove/attenuate frequencies outside band 1. EachADC 216 may be operable to convert the band 1 of the analog signal S toa corresponding digital representation. Operation of the RF front-end158 and/or processing of signals generated by the front-end 158, may,for example, be as described in U.S. patent application Ser. No.13/336,451 entitled “Method and Apparatus for Broadband Data Conversion”which is incorporated by reference herein, as set forth above.

In an example embodiment, the front-end 158A may reside in a cablegateway such as the cable gateway 120 described above. In an exampleembodiment, the front-end 158A may reside in satellite gateway/set-topbox and/or in an outdoor unit of a satellite reception assembly (e.g.,collocated on-chip or on-PCB with a satellite low-noise blockdownconverter (LNB)).

FIG. 2B depicts another example RF front-end of a receiver operable toperform spectrum monitoring in accordance with an example embodiment ofthe invention. The RF front-end 158B shown in FIG. 2B comprises avariable gain amplifier 252, a filter 254, and an ADC 256. Functionsperformed by the RF front-end 158B may be referred to as “full-spectrumcapture” (or “FSC”).

In the front-end 158B, the entire bandwidth, from F_(lo) to F_(hi), ofsignal S may be amplified by the amplifier 252 to generate S′. Theamplified signal S′ may be then filtered by the filter 254 to removeundesired signals outside of F_(lo) to F_(hi) and generate signal S″.The signal S″, from F_(lo) to F_(hi), may then be digitized by the ADC256 to generate signal D. In an example embodiment, the ADC may be asdescribed in U.S. patent application Ser. No. 13/485,003 entitled“Multi-layer Time-Interleaved Analog-to-Digital Converter (ADC),” whichis incorporated by reference herein, as set forth above.

In an example embodiment, the ADC 256 may be capable of digitizing asignal S wherein F_(lo) to F_(hi) is 1 GHz or higher. Accordingly, forcable television/DOCSIS, the ADC 256 may be operable to digitize theentire cable downstream (e.g., from ˜55 MHz to ˜1002 MHz). Similarly,for satellite television, the ADC 256 may be operable to digitize thereceived signal at the input of the LNB, and/or the downconverted signal(e.g., from ˜1 GHz to ˜2 GHz) at the output by an LNB.

FIG. 3 depicts an example channelizer which may be utilized forperforming spectrum monitoring in accordance with an example embodimentof the invention. Band selection filters 302 ₁-302 _(J) of thechannelizer 102 may each process the signal D to recover a correspondingone of the J selected bands of the signal D, and output the band on acorresponding one of the ports 304 ₁ to 304 _(J). A band selectionfilter 302 _(J+1) of the channelizer 102 may process the signal D torecover band C_(J+1) from the signal D, and output band C_(J+1) on theport 304 _(J+1). Which band or bands are selected by the filter 302_(J+1) may be configured based on one or more control signals input tothe channelizer 102. For example, the value of a parameter k maydetermine the center frequency of the portion of signal D that is to beselected as C_(J+1) by the filter 302 _(J+1), and the value of Δ maydetermine the bandwidth of the portion of this signal D that is selectedas band C_(J+1) for output on the port 304 _(J+1). In this manner, allof the signal D between F_(lo) and F_(hi) or any portion or portions ofthe signal D, may be selected for output on the port 304 _(J+1).

FIG. 4 is a flow chart illustrating example steps for spectrummonitoring in accordance with an example embodiment of the invention.After start step 402, in step 404, the receiver circuit 100 may receivea frequency division multiplexed (FDM) signal comprising one or morechannels (e.g., satellite television channels, cable televisionchannels, and/or DOCSIS channels) occupying a frequency band betweenF_(lo) and F_(hi). In step 406, the received FDM signal is digitizedacross the full band from F_(lo) to F_(hi). In step 408, the digitizedsignal is channelized into one or more bands. In step 410, a first oneor more of the bands are conveyed to a data processing module. In step412 a second one or more of the bands are output to a monitoring module.In step 414, the data processing module processes one or more of thefirst one or more bands to recover data on those bands while themonitoring module concurrently processes the second one or more bands todetermine characteristics of all or a portion of the frequency band fromF_(lo) to F_(hi).

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for spectrummonitoring

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputing system, or in a distributed fashion where different elementsare spread across several interconnected computing systems. Any kind ofcomputing system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computing system with a program orother code that, when being loaded and executed, controls the computingsystem such that it carries out the methods described herein. Anothertypical implementation may comprise an application specific integratedcircuit or chip.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method comprising: performing by one or morecircuits of a receiver coupled to a television and data service providerheadend via a hybrid fiber coaxial (HFC) network: receiving, via saidHFC network, a signal that carries a plurality of channels, wherein saidchannels comprise one or both of television channels and data channels;digitizing said received signal to generate a digitized signal;selecting a first portion of said digitized signal; selecting a secondportion of said digitized signal; processing said selected secondportion of said digitized signal to recover information carried in saidplurality of channels; analyzing said selected first portion of saiddigitized signal to measure a characteristic of said received signal;and controlling the transmission of network management messages back tosaid headend based on said measured characteristic of said receivedsignal.
 2. The method of claim 1, wherein said network managementmessages indicate whether a parameter is outside of acceptable bounds.3. The method of claim 2, wherein said parameter is a modulationparameter of said received signal.
 4. The method of claim 2, whereinsaid parameter is a transmit power of said received signal.
 5. Themethod of claim 2, wherein said parameter is a frequency offset of saidreceived signal.
 6. The method of claim 1, wherein said characteristicis signal power vs. frequency.
 7. The method of claim 1, wherein saidcharacteristics is signal phase vs. frequency.
 8. The method of claim 1,wherein said characteristic is one of: signal-to-noise ratio,peak-to-average ratio, noise levels, bit error rate, and symbol errorrate.
 9. The method of claim 1, configuring, by said one or morecircuits, a bandwidth and/or center frequency of said selected firstportion of said digitized signal.
 10. A system comprising: a receiverconfigured to be coupled to a television and data service providerheadend via a hybrid fiber coaxial (HFC) network, the receivercomprising: front-end circuitry operable to: receive a signal thatcarries a plurality of channels, wherein said channels comprise one orboth of television channels and data channels; and digitize saidreceived signal to generate a digitized signal; channelizer circuitryoperable to: select a first portion of said digitized signal; and selecta second portion of said digitized signal; processing circuitry operableto process said selected second portion of said digitized signal torecover information carried in said plurality of channels; monitoringcircuitry operable to: analyze said selected first portion of saiddigitized signal to measure a characteristic of said received signal;and control the transmission of network management messages back to saidheadend based on said measured characteristic of said received signal.11. The system of claim 10, wherein said network management messagesindicate whether a parameter is outside of acceptable bounds.
 12. Thesystem of claim 11, wherein said parameter is a modulation parameter ofsaid received signal.
 13. The system of claim 11, wherein said parameteris a transmit power of said received signal.
 14. The system of claim 11,wherein said parameter is a frequency offset of said received signal.15. The method of claim 1, wherein said characteristic is signal powervs. frequency.
 16. The method of claim 1, wherein said characteristicsis signal phase vs. frequency.
 17. The system of claim 10, wherein saidcharacteristic is one of: signal-to-noise ratio, peak-to-average ratio,noise levels, bit error rate, and symbol error rate.
 18. The system ofclaim 10, comprising configuring, by said monitoring circuitry duringoperation of said one or more circuits, a bandwidth and/or centerfrequency of said selected first portion of said digitized signal.